The detection of drowsiness is of importance because drowsiness impairs the ability of operators of a wide range of equipment including motor vehicles, aircraft and boats as well as industrial equipment
WO 03/039358 disclosed an alertness monitor that used infra red light to measure the amplitude and velocity of eyelid and eye movements to derive a measure of Drowsiness on a scale. This monitor sought to provide a real time alertness monitor that can provide a calibrated measure of the operator's alertness. There is a recent concern with the problem of driver distraction, not just drowsiness. By distraction they mean displacement of the driver's focus of visual attention from the driving task, either to a non-visual task (eg talking to other people in the vehicle, or the use of mobile phones), or to an alternative, visual task that reduces driving safety temporarily (reading a map or navigation system, adjusting a CD player or radio, etc). Thus, driver distraction is concerned with attention that is focused inappropriately, in direction and duration, for safe driving. The concept of a driver's incapacity seems to be applied primarily in the rail industry. It refers to some medical or other condition that makes the driver lose consciousness, not just enter the readily reversible states of drowsiness sleep, or distraction. This has been a major focus of interest in Australia after the a rail crash in which the driver died of a heart attack, but the train kept going and was derailed, killing passengers. The medical conditions that are most likely to be involved in such incidents are sudden death (eg heart attack or stroke), hypoglycaemia in diabetics, and epileptic seizures.
There is current system of vigilance detection in trains which involves the driver pushing a button or making some adjustment to the train controls (change speed, apply brakes etc) once every 90 secs (approx) or a siren will be sounded and the brakes applied to stop the train. However the drivers only have to be moderately alert for about 1 sec to push the button at any time during the 90-sec period. They could easily be asleep for a minute at a time, repeatedly, without this being detected by current system.
U.S. Pat. No. 6,102,870 uses eye tracker data such as fixations and saccades to infer mental states of the operator such as scanning, reading, searching, thinking and an intention to select. It is a system to enhance computer software responsiveness.
U.S. Pat. No. 6,346,887 uses a video based eye tracking system which tracks eye activity and pupil diameter and position to produce a signal representing eye activity that can be used to estimate alertness.
It is an object of this invention to provide an improved alertness monitor of the type disclosed in WO 03/039358 which can deal with incapacity.